Practical ECG methods

Question 1

What is an ECG electrode?

Answer 1

Tabs with a sticky back that are attached to cables/wires and stuck to the skin

Question 2

What is an ECG lead?

Answer 2

The graph

Question 3

What does the steepness of the ECG denote?

Answer 3

The velocity of the action potential

Question 4

What does a downward deflection mean?

Answer 4

The action potential is moving towards the negative electrode

Question 5

What does the isoelectric line represent?

Answer 5

No net change in voltage/change in direction

Question 6

What does a sharp turn represent?

Answer 6

Rapid change in direction

Question 7

What do upward deflections represent?

Answer 7

Action potential towards the positive electrode

Question 8

How many electrodes are attached to the body for an ECG?

Answer 8

10

Question 9

What does the P wave represent?

Answer 9

Atrial depolarisation and it is an upward spike as the positive electrode is situated near the apex of the heart

Question 10

What does the isoelectric line after the P wave represent?

Answer 10

Depolarisation of AVN

Question 11

What does the Q wave represent and why is it downwards?

Answer 11

Left bundle branch allows electrical impulse to go to the ventricles (septal depolarisation) towards the negative electrode. Very fast because very good conductor

Question 12

What does the end of the isoelectric line before the Q wave represent?

Answer 12

Bundle of His conduction

Question 13

What does the R wave represent?

Answer 13

Ventricular depolarisation via Purkinje fibres which is very conductive so fast – upwards peak as towards the positive electrode

Question 14

What does the S wave represent?

Answer 14

Late ventricular depolarisation but the spike is downwards as up the ventricle side via Purkinje fibers

Question 15

What does the isoelectric line after the S wave represent?

Answer 15

Fully depolarised ventricles

Question 16

What does the T wave represent?

Answer 16

Ventricular repolarisation occurs towards the negative electrode so upwards peak

Question 17

Where does lead 1 (ECG) go on the body?

Answer 17

Right arm to left arm

Question 18

Where does lead 2 (ECG) go on the body?

Answer 18

Right arm to left leg

Question 19

Where does lead 3 (ECG) go on the body?

Answer 19

Left arm to left leg

Question 20

Where does the v1 lead go?

Answer 20

Right sternal border in the 4th intercostal space

Question 21

Where does the v2 lead go?

Answer 21

Left sternal border in the 4th intercostal space

Question 22

Where does the v3 lead go?

Answer 22

Halfway between the v2 and v4

Question 23

Where does the v4 lead go?

Answer 23

Mid clavicular line in the 5th intercostal space

Question 24

Where does the v5 lead go?

Answer 24

Anterior axillary line at the level of v4

Question 25

Where does the v6 lead go?

Answer 25

Mid axillary line at the level of v4

Question 26

To calculate the QRS axis how many leads do you need and what angle must they be at?

Answer 26

2 leads are needed and 90 degrees apart (e.g. lead 2 and lead aVL

Question 27

Which leads are bipolar and which are unipolar?

Answer 27

leads 1-3 are bipolar and rest are unipolar

Question 28

Which leads are in the coronal plane and which are in the horizontal plane?

Answer 28

Leads 1,2,3 and aVR, aVL, aVF are coronal and all chest leads are horizontal